Edelbrock LD4B ?s

Bolt length = thickness of thermostat housing + diameter of bolt (then round up to nearest bolt length) So for example, thermostat housing is 1/2" and bolt is 3/8" you want 3/8-16 x 1" bolts.

A general rule of thumb it the minimum thread engagement should be the diameter of the bolt, or one complete thread visible on top of the nut with washer compressed.